Transparent film dressings are widely used as protective layers over wounds because they facilitate healing in a moist environment while acting as a barrier to contaminating liquids and bacteria. The films are also used as surgical drapes because of their barrier properties. Dressings and drapes fitting the above description are available under a number of trade names such as TEGADERM™ (3M Company, St. Paul, Minn.), BIOCLUSIVE™ (Johnson & Johnson Company, New Brunswick, N.J.), and OP-SITE™ (T. J. Smith & Nephew, Hull, England). The polymeric films used in those dressings and drapes are conformable, i.e., the films are extremely thin, flexible and supple. They are typically supplied with a releasable protective liner covering the adhesive coated surface of the film. When the liner is removed, the adhesive coated film tends to wrinkle and adhere to itself, interfering with the smooth, aseptic application of the dressing to a patient's skin. Various delivery systems have been proposed to address this problem such as those disclosed in U.S. Pat. No. 6,685,682. The use of a removable carrier, which does not require tearing of the film after it has been placed on the patient, avoids the problems described above. The carrier also aids in accurate placement of the dressing on a patient. Even with the carrier however, the dressings can be difficult to place on an irregular body surface, such as a joint (e.g., knee, elbow) or shoulder.
In addition, the length of time over which the medical dressings may remain in place over wounds may be limited by many factors. Among the factors that may limit the usable life of a medical dressing is the accumulation of fluids within the wound. Some medical dressings have included the use of negative pressure wound therapy in which fluids are removed from beneath the wound dressings without requiring removal of the dressings from the patient. Dressings adapted for delivery of negative pressure wound therapy (such as those described in, e.g., U.S. Pat. Nos. 4,969,880; 5,261,893; 5,527,293; and 6,071,267 (all to Zamierowski)) often have constructions that can compromise the sterility of the wound over which they are placed. These products often require a tube or wound drain that is introduced either through a multi-piece dressing or under a single piece dressing. In either case, it is difficult to obtain a good seal between the tube or wound drain and, during treatment, air can leak into the wound. That air can carry contamination into the wound and/or impair the effectiveness of the pressure-based therapy. These effects can be compounded by wounds on or around irregular surfaces, such as the knee, elbow, shoulders, heel, and ankle.
A need remains for a medical dressing that can be more effectively supported and/or more conformable for application to irregular surfaces, and particularly those associated with a joint, such as a knee, ankle or elbow, and particularly in wound therapy applications.